Electronic devices, including mobile phones and other portable devices, are increasingly being upgraded with improvised applications and functionalities. For example, a mobile phone may include a touch-sensitive screen that enables one to interact directly with what is displayed, rather than indirectly with a cursor controlled by a mouse or a touchpad. The touch-sensitive screen can sense fingers, hands, and passive devices such as stylus. Thus, the touch-sensitive screen can be used to activate a function of the electronic device.
In the present systems, activating a function of the electronic devices by a double tap using an accelerometer has been proposed for many mobile phones. However, in existing conventional systems, extensive studies in feature prototype have shown that it is extremely difficult to achieve low falsing in certain cases, such as, while the mobile phone is in pocket, car cradle, etc. In other words, falsing is hard to overcome in certain cases, for example, in the car cradle, because the accelerometer alone cannot distinguish finger tap and periodic motion generated from a rough road.